Fire performance of graphene/epoxy composites and feasibility for aerospace applications

Abstract

Graphene-based composites possess great potentials for applications in the aerospace industry owing to their superior properties. This thesis quantifies the effects of graphene nanoplatelets (GNPs) on the combustion behaviour of epoxy resin (ER) through a numerical modelling approach. Five different GNP/ER composites with different amounts and types of GNPs were prepared. At 3 wt% GNP loading, the peak heat release rate (PHRR) could be reduced by 47%. This drastic reduction in PHRR due to the GNPs is attributed to two principal contributions: (1) the reduced gas permeability slows down movement of volatiles to the surface to cause combustion, and (2) the reduced radiant conductivity of the GNP/ER char at high temperatures owing to GNPs being able to promote the formation of a continuous and compact char layer. This thesis ultimately provides a new method to quantify these two contributions focusing on the physical barrier effect of GNP in ER composites and ER char. A first simulation model based on the Lattice Boltzmann Method (LBM) and supported by X-ray CT and scanning electron microscope (SEM) images for geometry input, is developed and validated. The model can be used for predicting the gas permeability of GNP/ER composites at ambient temperature and the GNP/ER char during the combustion. The main conclusions in this respect are: (i) virgin composites with inclusion of GNPs in ER significantly decrease their effective gas permeability (66% reduction for 3 wt% GNP); (ii) aggregation of GNPs resulted in less barrier effect; (iii) GNPs reduced the gas permeability of ER char to one order of magnitude lower at 3 wt% loading. Radiant conductivity of the GNP/ER char is calculated by an analytical relation. Thermal and physical parameters of ER are optimised using a parameter optimisation method. The general pyrolysis model is then built to simulate the mass loss of GNP/ER composites under cone calorimeter testing. The reduction of PHRR due to GNP is numerically quantified, and agrees well with the author’s cone test results. The FDS simulations are performed to assess the potential of different GNP/ER composites for their capacity to pass the vertical burning test requirements and make them fit for aerospace applications. This numerical approach has shown a great potential to improve the material design process of graphene-based composites and is able to predict the fire behaviour of such composites in realistic fire conditions.

Date of Award	31 Dec 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Yong Wang (Supervisor) & Colin Bailey (Supervisor)